The Cure
by AvengerWarlockDetective
Summary: Ultron has been defeated, and the Avengers have gone their separate ways, only to be brought together again to fight a new threat – the mystical and deadly 'Cure' that turns friends into enemies and light into darkness. Even with the help of a certain consulting detective and a certain former army doctor, it seems like the Avengers have no hope of winning this time … Set after AoU.
1. Chapter 1

**Title : The Cure**

 **Author : AvengerWarlockDetective**

 **Fandoms : Avengers, Sherlock (BBC)**

 **Pairings : Anything canon to the MCU or Sherlock – Tony Stark/Pepper Potts, Bruce Banner/Natasha Romanoff, Clint Barton/Laura Barton, Thor/Jane Foster, John Watson/Mary Watson etc.**

 **Genre:** **Mostly Adventure, but maybe there will be a bit of Crime (this _is_ Sherlock), Fantasy or SciFi (this _is_ the Avengers), mild Romance, and possibly some Humour and Angst if I actually manage to be good at either. This is just a big mix of genres, deal with it. **

**Disclaimer : No, I do not own Marvel, the Avengers or Sherlock – if I did it would be incredibly awesome and I would probably be the happiest person on the planet, but unfortunately I don't. Strangely, this is _Fan_ Fiction, so if I actually owned them, I don't think I would count as a fan, and I certainly wouldn't be writing FanFiction about my own characters. Because that would just be weird.**

 **Author's Note : Hey guys (if I actually _get_ any readers … oh well)! Sorry for the long introduction here – it definitely won't be like this every chapter, just occasionally an Author's Note. I just wanted to have all my pairings included because I know some people don't like to read fanfics with particular relationships. This is set immediately after Age of Ultron (and Series 3 of Sherlock, but presumably most people have seen that), so it WILL contain spoilers! This is my first fanfic so constructive criticism is welcome! I have no idea how often I will update this, maybe once a week? Anyway, most chapters will be between 1000 and 2000 words, but that's just for now and they will probably vary. Enjoy!**

 **AvengerWarlockDetective xx**

* * *

Chapter 1

"John, there's no such thing as 'magic', and you're not going to convince me otherwise!" Sherlock Holmes folded his arms and glared at the doctor accusingly, signalling the end of the conversation.

John sighed and pinched the bridge of his nose, ignoring the glare. Sherlock Holmes, despite being a genius and probably the smartest man on the planet, could be _ridiculously_ narrow minded sometimes. "Yes, as you've said about seven-million times already." He ignored Sherlock's muttered comment of 'Seventeen, actually', and continued. "But all the evidence leads to a dead end and _surely_ magic is the only possible explanation?"

"Yes, yes, certainly," Sherlock grumbled sarcastically, spinning back around in his chair to shuffle through a stack of photographs on the table. "It's _definitely_ the only possible explanation."

John growled in frustration. "Is this where you tell me how stupid I am again? If it's not magic, then what is it, Sherlock? What do _you_ think?"

"Well, it's obvious," the sociopath said patronizingly, not looking up from his work. "This 'Loki Laufeyson' fellow is clearly intelligent – look at the focus of his eyes! The way he assesses the situation before taking action … he's very clever, if not a genius. So we know if he wanted to do something criminal, he'd be able to do it well. Which brings us onto our next point, his motives …" The consulting detective held up a photo of two men, the dark-haired Loki and a more muscular blonde one. "The blonde is Thor Odinson, part of a top-secret branch of the American government, the Strategic Homeland Intervention, Enforcement and Logistics Division."

"They need a new name," John commented. "And if it's top secret, how do _you_ know about it?"

Sherlock ignored him. "If we assess the way Odinson acts around, talks to, and even _looks_ at our criminal, it infers that they have known each other for a long time, if not their entire lives. So, this brings us to assume that they are brothers. However, we can tell that they are not genetically related by the fact that their physical features are so completely different that it's almost impossible they are siblings. We –"

"Why do you keep referring to yourself as 'us' or 'we'?" John asked, smirking.

Sherlock glared at him this time. "Shut _up_ , John! _As I was saying_ , we can assume that Laufeyson is adopted …"

John absent-mindedly fiddled with a piece of paper that had been left on the coffee table, folding it into various different origami shapes, and his mind drifted. Instead of thinking about the international criminal, he began thinking, for some unknown reason, about Winnie the Pooh. Even when he started humming the theme tune under his breath ( _A donkey named Eeyore is his friend, and Kanga and little Roo. There's Rabbit, and Piglet, and there's Owl, but most of all Winnie the Pooh … Winnie the Pooh, Winnie the Pooh …_ ), Sherlock didn't even notice his friend wasn't listening and continued to drone on about his deductions of Loki.

"So, John! I told you that was a much more plausible explanation!"

John blinked, looking up from his piece of paper. "Uh … sorry?"

Sherlock sighed. "Loki Laufeyson was the adopted brother of Thor Odinson. Thor was treated better than him by their father, probably given all of their father's inheritance, which activated psychopathic tendencies which Loki had been harbouring his entire life. Psychopaths often have a particular mind set, but it's often not visible until later in life. Loki, feeling isolated and unwanted, decided he would strike fear in the heart of the people of New York by pumping hallucinogenic drugs into the water system, meaning that people _thought_ they saw aliens pouring out of a wormhole in the sky and superheroes flying around and a big green monster thing, when really it was just drug-induced images. Meanwhile, Loki set explosives off in various parts of New York, which is what caused all the damage. See? Makes much more sense than 'magic'."

John put his head in his hands. "No, Sherlock. No, it really doesn't. Nor does it make any more sense than all your other theories about it. _Including_ the one about all of it being a messed up government conspiracy plot, and that one was _weird_." He reached for his mug of tea, and grimaced when it was cold. How long exactly had Sherlock been talking? "Anyway, why _are_ you getting so hung up on this? It was _three years ago_ , for god's sake. Can't you just accept what the press told everyone?"

"No, I can't!" Sherlock said violently. "It doesn't _make sense_!" And with that, he slammed the photographs down on the table and stormed out of the door.

"Uh, Sherlock?" John called. "Where are you going?"

"Out!" came the reply, before the front door slammed.

John sighed and flicked the TV on. There had been no point whatsoever in even coming to 221b this afternoon. He should have known that all Sherlock would want to talk about was the event in New York. The consulting detective had, surprisingly, only found out about it recently, as he was too busy solving the Moriarty case at the time. Since then, he had been brainstorming theories about it over and over again. It was, apparently, really bugging him.

John was snapped out of his musings as the headlines appeared on the TV.

" _Breaking news: Yesterday afternoon, a terrifying and bizarre event happened in the region of Sokovia in Eastern Europe_ ," the female newsreader said in a crisp monotone. " _An entire city was elevated almost one-thousand feet from the ground by a form of immensely powerful, and, as of yet, unheard of electronic system, whilst the city's residents were attacked by flying robotic drones which could be a form of artificial intelligence_."

The screen showed a shaky clip of a huge drop down to mountain scenery, as man-sized robots flew around them, shooting lasers at people. John stared. "What the hell?"

" _Once again, the day was saved by the world-famous 'Avengers', who first made their appearance in New York three years ago, who go by the aliases, 'Hulk'; 'Black Widow'; 'Hawkeye'; 'Thor'; the ex-CEO of Stark Industries, Tony Stark, known as 'Iron Man; and the revered WWII super soldier, 'Captain America'_." There was a shot of a young woman wielding red energy in her hands, her eyes glowing the same shade. " _This mysterious woman has also been sighted, recently identified to be the orphaned Wanda Maximoff, twin sister of Pietro Maximoff, who died in the battle_."

The clip cut off to switch back to the newsreader. " _The Avengers saved more than five thousand people yesterday. However, there have been more than a thousand fatalities and almost two hundred deaths. For more updates on the crisis, tune in to BBC One News at 6 O'clock_."

The news finished and an advertisement started. Numbly, John flicked the TV off and stood up. "Not magic, huh?" he mumbled to no one, as he left the apartment and descended the steps to the front door. There was _no way_ that Sherlock could explain this now. That girl - Wanda Maximoff - was controlling weird red energy! How was that _not_ magic?

He needed to find Sherlock.


	2. Chapter 2

Chapter 2

When Sherlock's phone rang, he ignored it. It was a fact that had only recently been accurate, as in the past few weeks, the detective had decided that having long-winded and boring phone conversations were unnecessary and, quite frankly, a waste of time. He had more important things to worry about at the moment – two important things, in fact.

One, Moriarty. After his sinister message last year, James Moriarty had disappeared without a trace, and Sherlock _still_ didn't know whether or not his nemesis was actually ever alive in the first place. There had been no leads, no signs, nothing.

Two, the New York incident. When he'd found out about it a month or so before, he realised it was a perfect opportunity for a case – they'd had hardly any work recently, and he was bored out of his brains. Anyway, it was perfect, because everyone else in the world had been buying the rubbish that the press was telling them, and no one had even considered that there may be a more rational explanation. And, of course, if no one had solved the case _properly_ , the criminal was most likely still at large, and dangerous. There had been no police reports about Loki Laufeyson going into custody … no records, even, of a court meeting or sentence at all. He had simply _disappeared_. Rather like Moriarty.

Back to the point: it was a fact that if Sherlock's phone rang, he didn't answer it. So, when his _incredibly_ irritating ringtone started blaring out from his coat pocket – had John changed it? It wasn't like that usually – he simply ignored it and carried on walking. He knew exactly where he was going, and he didn't like it, but John was stubbornly insisting that the New York case was caused by _magic_ , so Sherlock needed evidence from someone who he was reluctant to talk to before.

The phone finally stopped ringing, and the consulting detective sighed in relief, only to curse in annoyance when it started ringing again.

"Oh, for god's sake!" he snapped, as he fished it from his pocket, startling a few pigeons and a teenage boy, who gave him a weird look. Sherlock ignored him and accepted the call. "Yes, what do you want?"

"Most people say 'hello' when they answer the phone," John said at the other end of the line. "It's considered polite."

Sherlock sighed irritably. "I hope there's a good reason for this. I'm busy."

"Doing what? And, yes, there is," the doctor continued, not waiting for an answer. "I just turned on the news, and guess what happened yesterday in Soak … Sock … Sook …"

"Sokovia?" Sherlock supplied helpfully. "Eastern Europe?"

"Yeah, that was it. But the point is, an entire city was levitated one thousand feet off the ground!"

"Preposterous," scoffed Sherlock. "That's impossible."

"Well, apparently not. Guess who saved the day again?"

"The 'Avengers'?" the detective said sarcastically, doing air quotes with his fingers at this point even though John couldn't see him, and almost dropped the phone.

"Um, yes, actually."

"Oh!" Sudden realisation hit him. " _Oh_!"

"What?"

"That's it!" Sherlock exclaimed. "That must be it! These Avengers have now been involved in at least two life threatening events … supposedly being the _heroes_ … how do we know that _they_ aren't the ones behind it?"

"Don't start off again, Sherlock," John started saying exasperatedly, but Sherlock hung up, quickening his pace. The person he was going to see might have the answers.

He was at his destination in less than fifteen minutes, after taking a ten minute taxi trip and then walking again. Sherlock reached the front door of the large, office-like building, where a guard was stood on the steps.

"Sherlock Holmes," the sociopath said, holding up an ID card. "I'm here to see Mr Mycroft Holmes … is he in today?"

The guard checked a list. "Yes, he is. Office 7H, top floor."

Not bothering to thank him, Sherlock strode past into the building, and took the lift to the eighteenth floor. Once up there, his eyes scanned the names of the offices – more out of habit that the fact that he actually _needed_ to – until he reached Office 7H. He knocked twice on the door, then opened it anyway.

Mycroft Holmes was talking to someone when Sherlock walked in, a man that the detective didn't recognise, who was sat opposite Mycroft across the desk. They both looked round when Sherlock walked in.

"Sherlock! Most people wait to be asked in after knocking!" Mycroft scolded his younger brother. "It's considered polite."

"Says the man who always lets himself into my apartment without even being invited," Sherlock shot back (rather childishly, he knew, but Mycroft was _very_ annoying). "Who's this? How long will you be?"

The man stood up. He was black, and bald, with an eye patch covering his scarred left eye. He was dressed all in black, with a knee-length leather coat, and a gun holster strapped to one leg. "You don't need to know my name," he said in an American accent.

At exactly the same time, Mycroft said, "This is Nick Fury."

Nick Fury glared at Sherlock's brother. "Hey, you ruined my 'badass, mysterious secret agent' persona!" At Mycroft's bemused expression, he grinned. "Only joking, Mr Holmes." Fury turned back to Sherlock. "Yeah, what he said. You can call me Director Fury. Well, anyway, you must be Sherlock. I've heard a lot about you."

"Um … right." For once, Sherlock was lost for words. He narrowed his eyes, frowning, but he couldn't seem to read anything about the Director. "Why exactly would that be?"

"I'm here to talk to you about the Avengers Initiative." Fury said this in a way that was supposedly intended to sound dramatic, but Sherlock barely heard him.

"Yes, I supposed you are," Sherlock said distractedly, still searching for information, but it seemed impossible to deduce this man. After a moment, he gave up, and looked back up, into Fury's one eye. "Sorry, what was that?" he said, smiling innocently as if he wasn't at all frustrated and confused.

Director Fury sighed, and put his hands on his hips. "The Avengers Initiative, Holmes. I'm offering you a place in it. Though I'm already serious regretting this already."

Sherlock raised his eyebrows. "The Avengers? You mean the group of international criminals who have most likely been arranging ridiculously impossible, fake events to gain fame for themselves?"

The two older men stared at him.

"I'm sorry … what?" Fury demanded.

"You appear to be incorrect, brother," Mycroft said, looking amusing. "Are you losing your touch?"

"No, I'm not, thank you very much!" Sherlock hissed, folding his arms.

Fury rolled his eyes … um, eye. "You two remind me of another pair of brothers I know."

"Thor Odinson and Loki Laufeyson," Sherlock said immediately, shooting a smug look at Mycroft. "Although they're not actually brothers, are they? Laufeyson was adopted."

Looking quite impressed, Fury nodded. "Yep, that'd be them. You worked all that out, did you? Well, if you know about our two alien brothers, than you most likely already know about the Ultron incident, am I right?"

Sherlock restrained himself from asking about the man's use of the word 'alien', not wanting to come across as even more confused than he already was. "Ultron? Um … no, actually."

Mycroft put his head in his hands. "I'm ever so sorry for dragging you over to Britain, Nick. I thought my brother might actually be a possible candidate for joining the Avengers, but apparently not."

"The Avengers," Sherlock interrupted. "Who exactly are they, if they're not criminals or part of the US government? None of my evidence has been adding up, which is _incredibly_ unusual as I've never not solved a case before."

"Superheroes, Holmes. They're superheroes."


	3. Chapter 3

Chapter 3

"We're not damn superheroes!" Captain America exclaimed angrily.

"Language," Sam Wilson commented, smirking slightly.

Steve span round and glared at him. "Why the hell is everyone in on that joke?"

"Language!" Sam repeated, folding his arms and struggling to keep a straight face.

"Oh my _god_!" the super soldier snapped in exasperation.

" _Language_ …" Sam whispered.

Steve wanted to punch him, and very nearly did, managing to restrain himself. "Shut _up_ , Sam! All I'm saying is … ugh, now I've forgotten. Thanks for that! It was important!"

"You said that we are not superheroes," Wanda Maximoff reminded him. "You said that people call us superheroes, but we are not. You were ranting about it."

"Thank you, Wanda!" Steve said. "See, Wilson, at least _someone_ in our stupid little group isn't being absolutely annoying today!"

"I stick with my point, though," Sam said, shrugging. "If we're not superheroes, then what are we?"

" _Normal people_!" Steve protested.

"No, wait, hear me out, Cap. There's _you_ , enhanced super soldier, me and War Machine here –" He patted James Rhodes on the back. "— both have high-tech suits which allow us to kick ass, and _fly_ … superheroes fly, Steve … Widow –" He gestured at Natasha who raised her eyebrows sceptically. "She's got all her assassin-y stuff and … yeah, well, Wanda can do _mind control_ , for heaven's sake, and telekinesis! How the hell is that not a _super power_?"

Wanda shrugged slightly as if to say 'He's got a point'.

"And finally, we've got the Vision … he's a, uh, what was it? Synthetic humanoid? Well, anyway, he can fly, shoot people with his yellow gem thing and he has a _cape_! Superheroes have capes!"

The Vision frowned. "I am unsure as to why I have been brought into this irrelevant conversation. Remind me why exactly we are arguing … I apologise, why _you_ are arguing about this subject? Aren't we supposed to be training?"

"Because these men, they are being idiots," Wanda said simply, before turning around and walking out of the training room, the doors slamming shut behind her with red energy.

"That was the most accurate statement anyone has made in the last twenty minutes," Natasha agreed, folding her arms. "Look, guys, why don't we just stick with 'We are neither superheroes nor not superheroes,' and leave it at that."

Sam and Steve stared at her. "That doesn't even make sense!" they cried in unison, before glaring at each other.

Rhodey rolled his eyes. "Well done, Agent Romanoff. You just made everything a hell of a lot worse." He raised his eyebrows at Sam and Steve. "How did this start again?"

"Sam said we were superheroes. We're not," Steve told him.

"Explain the _Hulk_!" Sam insisted.

"Failed medical experiment!" Steve snapped back.

"Thor, then!"

"Sh*t, Sam, he's from a _different world_!"  
"Language!"

"If you say that _one more time_ …!"

They were interrupted by the door opening suddenly and Tony Stark entering. "Hey guys! Just looking for my …" He stopped as he realised everyone was looking at him and the room was totally silent, the Falcon and Captain America both looking furious. "Uh, am I interrupting something?"

"They appear to be quarrelling over trivial matters," sighed Vision.

"Jeez, I leave for …" the billionaire glanced at his watch. "Less than five hours, and when I get back everyone's at each other's throats! And, no, I'm not staying, I just came back to pick up my stuff, which I _somehow_ managed to leave in here … kind of destroyed my entire emotional and dramatic 'farewell', I guess …" Tony trailed off, glancing around the room. "Small red suitcase, anyone seen it?"

He was given blank looks in return.

"Stark, are we superheroes or not?" Steve said, breaking the awkward silence.

"Oh! Found it!" Tony spotted his suitcase and grabbed it, before returning to the door. "What? Superheroes? Yeah, we're definitely superheroes." He winked at them all before exiting the room, chuckling.

"See!" Sam exclaimed. "If Tony Stark says so, it must be true!"

"What makes _his_ word 'law'?" Steve retorted.

Natasha shook her head, and followed Tony, leaving them to argue. "We really are the worst team of 'Earth's Mightiest Heroes' the world has ever seen."

* * *

"Tony! Wait up!"

The genius stopped mid-step and span round on his heel. "Yes, darling?"

Natasha caught up with him, eyebrow arched. " _Darling_?"

Tony grinned at her as they continued walking down the corridor together. "That's what I said, sweetheart. Okay, okay, I'll stop! Don't give me the evil eye, it's terrifying. Anyway, are you in need of my fantastic skills and awesome talents?"  
The assassin rolled her eyes. "You're unbelievable."  
"I know."

" _Shut up_! Anyway, yeah. I wanted to know how Pepper was."

"Um, she's fine. Though she's slightly pissed that I didn't tell her about the whole Ultron thing … and let her return to an empty and partially destroyed Avengers Tower _still_ without knowing what was going on … and simply the fact I invented a 'Robot of Death', as she so glamorously put it, which almost wiped out the human race … and I flew to Europe without telling her and not calling … Okay, she's more than _slightly_ pissed. She's _majorly_ pissed. Why do you want to know?"

"Oh, she's my friend," Natasha said breezily as they exited the front doors of the Avengers HQ into the bright summer sunshine. "Wanted to see if she was okay, you know, the usual."

"For a spy and assassin, you can be a really bad liar sometimes," Tony told her. "Pepper's not the reason you're talking to me, is it, Widow?"

The redhead bit her lip. "Maybe not …"

Tony sighed. "Bruce?"

"I wanted to know if you'd heard from him. It's just … we've had no word here, and as you two were … _are_ … like best friends, I thought –"

"Natasha," he interrupted. "It's been five hours, like I said. It's incredibly unlikely that Bruce would have contacted me in that time, and he hasn't. But I promise that when he does … _if_ he does … I will call you right away. But, Shelob –"

"Did you really just ' _Lord of the Rings_ ' reference me, Stark?" Natasha cut in.

"Yes, actually. What do you have against it? It's like the best book and film ever. But, as I was saying, Bruce doesn't want to be found. He's gone off on his own, and if he wants you to know where he is, you _will_ know. Just … don't get hung up on it, okay? You'll feel a lot better about it."

She nodded, looking downcast. "I guess you're right."

"Aren't I always? Seriously, though, it's not like he's gone forever. We know Dr Smashy, and he'll come back, eventually. He's like a boomerang. A boomerang with extraordinary anger management issues that turns into a larger, scarier, greener boomerang. Everything's gonna be fine, Ginger Snaps."

"I hate your nicknames," Natasha grumbled as they reached the road where Tony's car was parked. "How the heck do you come up with all of them?"

Tony flashed her another smile, sitting behind the wheel and starting the engine. "What can I say? I'm incredible in so many ways!"  
She shook her head, grinning. "And modest, too."

"Well, don't let the others kill each other. If there's an argument, break it up. If there's a fight, knock them out. If there's a war … uh, take the side that you agree with most and contain it so it doesn't involve the entire country. You catch my drift?"

"Try not to piss Pepper off further," she replied jokingly.

Tony laughed. "Easier said than done."

Natasha watched as he drove off and disappeared round the corner, feeling slightly better about the whole Bruce thing. It was probably just simply _seeing_ one of the old team that had done it. There had been an odd sense of … _closure_ this morning, that she wasn't quite sure that she had liked: Thor returning to Asgard, Tony going back to Pepper in Manhattan, Clint leaving for his farm and family, and Bruce already gone, of course. All that was left of the original team was Steve and herself, and although they had all the new recruits, it was kind of depressing. They were her friends – the only real ones she had ever had, to be quite honest, and she didn't like losing them.

The assassin headed back for the building, before deciding to take a walk around the grounds instead of returning and having to face everyone's stupid bickering.

That was when her phone rang.

In a flash, she retrieved it from her pocket, heart hammering wildly. _Unknown number_ , the screen read. Oh my god. Could it be …?

"Hello?" she said, answering it. To her dismay, the image of Nick Fury appeared on the holographic screen. "Oh. Director Fury. Hi." Natasha tried her best not to sound disappointed, and being an incredibly skilled actress, succeeded.

"Agent Romanoff," Fury said. "We have a new recruit on the team."

"Oh?" she replied, not showing that she didn't actually care in the slightest. They were all _replacements_. Natasha hated the fact that Fury was doing that. _Replacing everyone_.

"His name is Sherlock Holmes. I'm sure you will get on just fine, he's a great guy."

Natasha heard someone mutter something in the background, and someone else laugh. Fury rolled his eye before continuing.

"I'd ask Rogers this, him being the leader and all, but his phone's off for the fiftieth damn time - does he even know how to turn it on? Anyway, I'd like you to tell him and the others that we need a few of you – four would be good, leave two to guard home base – in Singapore tomorrow. There's something there that I'd like you and Holmes to sort out … just as a little assessment for our newbie."

"What's the issue?"

"I'll tell you when we get there. But it's important, believe me. Meet us outside the airport at 1100 hours on the dot. Your flight's already sorted."  
"Okay," she replied, slightly confused, and he hung up.

* * *

 **A/N: Yay, the Avengers are finally in the story! Sorry about the randomness of this chapter ... I guess the first part of it was kind of like a one shot, and didn't exactly add much to the plot, but I promise the plot will continue in the next chapter! I don't really know where the 'We're not superheroes' thing came from, I can just imagine that Steve wouldn't agree with the label 'superhero' for some reason. He's so modest. :)**

 **Sorry for the abrupt ending for this chapter, I wasn't sure how to wrap it up.**

 **Please review if you like it (you'll get virtual, imaginary cookies!) ... or review even if you don't like it ... I'd love some feedback.**

 **Thanks to alexis for being the first to review - I'm glad you like it so far!**

 **AvengerWarlockDetective xxx**


	4. Chapter 4

"Pack up John, we're going to Singapore."

Sherlock stepped out of a taxi directly in front of 221b Baker Street, striding past John, who was still waiting on the pavement, where he had been trying to call Sherlock repeatedly and failing. John spun on his heel and followed his friend without missing a beat, though practically jogging to keep up with the consulting detective's long stride.

"Singapore? What? Where were you? What's going on?"

Sherlock opened the door, not bothering to hold it for John. When the doctor had recovered from having a heavy door slam abruptly in his face, he ran up the stairs to Sherlock's apartment. The detective was throwing his things into a suitcase with careless abandon, not folding anything or putting anything in neatly (to John's great displeasure).

"I've joined the Avengers. We're going to Singapore. Plane leaves in half an hour."  
John stared at him.

Sherlock zipped up his suitcase and made for the door, before realising that John hadn't moved. "What are you doing? Hurry up! We need to go!"

"Sherlock," John said slowly. " _You've joined the Avengers_?"

The sociopath glared at his friend impatiently. "Yes, you idiot, weren't you listening? Pack!"

"My stuff's at home …" the doctor said helplessly, bewildered.

Sherlock handed him another suitcase. "Ah, yes, I forgot. I've already got your stuff. Clothes, camera, money, toiletries, clean underwear, the book you're reading at the moment, diary, notebook and pen. It's all in there. Come on, let's go."

He left John standing there, holding the suitcase, staring blankly at the door. What the heck was happening?

" _John_!" Sherlock yelled from the front door.

"Coming!" he replied, grabbing the suitcase and sprinting after Sherlock.

* * *

" _Fifteen hours_?" Sam groaned, shoving his suitcase under the table on the plane and throwing himself ungracefully into the window seat. "This is S.H.I.E.L.D.! Surely we have some kind of … faster, secret agent plane?"

"This isn't S.H.I.E.L.D," Steve reminded him, sitting next to his friend. "S.H.I.E.L.D. was compromised, and most of their aircraft was destroyed anyway. This is the best we can do."

"I'm used to flying as the Falcon, Cap," Sam grumbled, folding his arms. "I'd get to Singapore in less than three hours if I was using my suit."  
"You guys are in really bad moods today, huh? You've been arguing all afternoon." Natasha joined them on the opposite side of the table, followed by the Vision, who was looking around, frowning. She placed a file on the table. "Agent Hill just gave me this. It's about our new member."

The jet plane took off, and New York shrank beneath them.  
Steve reached out for the file and slid it towards himself. "No information about our actual _case_ yet? I thought that would be slightly more important. We need information about what we're facing here. Is it a crime to be solved or a villain of some sort that we need to fight, or what?"

The assassin shrugged. "It's all confidential until we reach our destination." She gestured at the file. "So what's the deal on our most recent addition?"

Steve opened the file. A photo of a man with curly, dark hair and a thin, intelligent face looked out at him, frowning slightly. _Sherlock Holmes_ , the title of the first page read. _Possible candidate for the Avengers Initiative. 38 years old, male, consulting detective. Currently inhabits apartment 221b on Baker Street, London, England._

"A detective?" the super soldier said out loud, frowning. Why would Fury put a _detective_ on the team? There were already plenty of detectives working with Fury and the Avengers. What made _this guy_ so special?

"A _consulting_ detective," Sam added, peering over the Captain's shoulder at the page. "What the hell's that?" he asked, looking at Natasha.

"Why do you expect _me_ to know, Wilson?" she said drily. "How about asking our _Artificial Intelligence_ here?"

The Vision looked up from analysing the table – or whatever he was doing, Steve didn't understand that guy – and glanced at the file. "Sherlock Holmes is the only consulting detective in the world, and a genius, actually, who has prevented and solved many hundreds of crimes, with the assistance of the former army doctor, John Watson. I believe Fury would want him to join the Initiative because of his intelligence. However, this doesn't appear to fully add up as we already have two geniuses and, if I may say so, myself on the team. "

Sam stared at him. "How did you work all that out from just _looking_ at him?"

The Vision raised an eyebrow. "All I needed was an image of his face to research him."

" _Research_ him?"

"Yes. When I was Mr Stark's personal artificial intelligence, I had access to every megabyte of data on the internet, and because of the photographic memory that I possess, I am able to recall these facts. Mr Holmes and Mr Watson each kept a blog of their cases and experiences, so therefore I hold information on their lives."

Sam shook his head. "This is too weird. I'm never going to understand him."

Steve held up the file. "If he's a genius, then maybe he's here to replace Bruce? We don't have Banner's brain on our side anymore, as he's … wherever he is … so that could be why Fury wants him on the team?"

Natasha flinched. "It's not like Bruce is gone for good, Steve."  
"No, of course not," Cap replied hastily, but he didn't fully agree. Bruce didn't show any signs of wanting to return when he had flown off. Steve kind of doubted that they would hear from him any time soon. "But still …"

There was a moment of silence as they all stared out of the windows or into space, lost in thought (except Vision, who appeared to be inspecting the wood of the table again, for whatever reason), and then the four of them (except Vision, who didn't look up from his wood grain counting, which was Steve's theory on the synthetic humanoid's odd behaviour) jumped out of their skin when Natasha's cell phone rang.

She grabbed it. "It's Wanda." The assassin answered it, flicking it onto speaker. "Hello, Natasha Romanoff speaking."

"Of course it is you, Agent Romanoff," Wanda hissed from the other end of the line. "I am calling your mobile, am I not? Who else would it be?"

Steve could see the back of the holographic image on Natasha's phone, and he frowned, sensing something was wrong. Wanda's usually pale cheeks were flushed pink, and her eyes were darting around her surroundings. The image itself was shadowed – was she in a dark room?

"Sorry, Wanda," Natasha sighed. "Why are you calling me, is something wrong?"

"Yes," the Inhuman replied, her eyes wide. "Yes, something is _very, very_ wrong indeed."

"Wanda," Steve said. "Tell us what's happened. Has someone attacked the headquarters?"

She shook her head frantically. "No, Captain Rogers, there has been no attack. That is not what has happened … I do not understand what is going on here. Though it is something bad. They are all …" The girl whimpered. "Ah, I do not know. They are not _dead_ … they are …" There was a muffled shriek and a scuffle of feet. Wanda's face disappeared from the screen for the moment as blurred images took her place. It sounded like she was running.

"Wanda?" Natasha said urgently.

The blurred images stopped and Wanda appeared in the phone screen again. "I am sorry. Do _not_ come back. Just … don't, please. Please, Agent Romanoff." She glanced over her shoulder, tears beginning to trickle down her cheeks. "Agent Hill and the War Machine are already down. Everyone is." Wanda paused, looking back at the camera, wide, fearful eyes beginning to glow red. "Now, they are coming for me."

The screen went black.

* * *

 **A/N: Hey guys! Thank you to my two new followers and both reviewers!**

 **Anyway, all I know about Vision is from Age of Ultron, as I haven't read any of the comics with him in. Because of this, my knowledge of his powers and stuff is pretty limited, so if I give him a power that probably isn't canon (i.e. 'mentally researching people' like in this chapter), sorry. I'm just gonna assume he can do that kind of stuff, being JARVIS in the past and all.**

 **Also, I don't know if it really takes 15 hours to fly from New York to Singapore, but whatever.**

 **If you review you are worthy of the power of Thor! ;)**

 **AvengerWarlockDetective xx**


	5. Chapter 5

**Hey everyone! Sorry I've not updated for ages (so much for updating once a week), but here's the new chapter! Thanks to everyone who has reviewed, favourite and followed!**

 **fastreader12 asked if there were zombies, and well, kind of, but not quite ... but you'll have to wait and see! :D**

* * *

Chapter 5

"What's happened to them?" John breathed in horror, staring at the hundreds of bodies that greeted them at the airport. "What … oh my god. Are they _dead_?"

"They're breathing," Sherlock noted. "So no. Simply unconscious. There are no signs of wounds or attack, no injuries of any description … nor is there any connection between the victims. Age … gender … race … social status … it would have to have happened to all of them, simultaneously, to wipe them out like this. Gas, possibly? No, there would still be residue in the air, this happened recently …" He weaved his way through the bodies, murmuring to himself.

John and Director Nick Fury stood at the door that they had come through from the plane tunnel, both watching Sherlock. John mentally kicked himself for asking if they were dead. He was a doctor. He should know this stuff. Now Fury probably thought he was an idiot. John crouched down by one of the bodies, inspecting it.

"He's right, there are no visible signs of attack," John noted, reaching out to roll the unconscious woman over.

"NO!" barked Fury. "Don't touch the bodies!"

But it was too late, and John's fingertips had already touched the woman's shoulder, and he leapt backwards, hissing in pain. The skin across his fingers was red like he had been burnt. It certainly _felt_ like that. "What the heck was that?"

Fury sighed. "Well, this isn't our average attack, Dr Watson."

Sherlock looked over to them in interest, and John stood from his position by the body. "What do you mean?" the doctor asked, frowning. "What happened here?"

"Back at the Avenger's headquarters, they received a red alert message from this airport. When our agents tapped into the CCTV for the building, they saw a man exit a train at the northern border of the country at eleven fifty six yesterday morning. Everything looked normal, until this guy closed his eyes and held out his hands." The Director paused, looking kind of reluctant to continue.

John raised his eyebrows. "What? What happened then?"

"Well, this … energy, like black smoke, or shadows, maybe, began flowing out of his hands. It knocked out everyone it touched. He could control it, warp its shape and its direction of travel, which didn't look dissimilar to Scarlet Witch's power. When everyone in the room was unconscious, the man turned and left the building, and proceeded to wipe out the entire city. I have no idea if has been contained since then, or whether the problem has spread into the rest of Asia. The man hasn't been seen by any CCTV since. We need you two to work out what's going on here."

"It could be a weapon," Sherlock mused. "But what use is a weapon that only knocks people unconscious? Presumably they'll wake up at some point. What happens afterwards – the unconsciousness could be just … a symptom, possibly? It could be an illness of some kind, in the form of this energy you described, a disease that can be transferred by air in a matter of seconds, rendering the victim unconscious."  
"Perhaps," Fury agreed. "But there's no disease that I know of on Earth that acts like this. I'm guessing this is supernatural in origin."

"Why exactly do you need our help?" the detective said smoothly. "Dealings in the supernatural isn't exactly our area of work."

Before Fury could answer, the double door to the 'Arrivals' section of the airport swung open and four people entered. Three of them looked pretty normal – a tall, muscular blonde man, whom John recognised as Captain America; a slim, pale, red haired woman, Black Widow; a tall man with short black hair and cheerful eyes – the Falcon, John thought his name was; and, most strangely, a ... could it be described as a man? It wore a long cape, had a yellow stone set in its forehead, and its skin was deep crimson and dark turquoise. And the thing was _floating_.

"What the heck," John murmured, staring.

"Sherlock Holmes, John Watson," Fury announced, gesturing at the two of them. "Meet Steve Rogers, Natasha Romanoff, Sam Wilson and the Vision."

Natasha Romanoff, the Black Widow, looked around in shock. "What exactly happened here, Fury? Is the situation we need to sort out?"

As Fury explained their theory (well, Sherlock's theory) to the four of them, John watched as Sherlock 'deduced' them, muttering under his breath. Even from where he was standing ten metres away, John caught snatches of the detective's deductions.

"Soldier from WWII, enhanced stamina, speed and strength … lost childhood friend … America … out of time … super soldier …"

He was just _describing_ Captain America, jeez. There was _no way_ that Sherlock had not heard of the legendary soldier. John rolled his eyes.

"Air force … suit … enables to fly … works with PTSD sufferers …" Sherlock had moved on to the Falcon now, his eyes flickering over the man so fast that his pupils were blurred. Then the sociopath's gaze moved onto Natasha, and he paused, frowning. Sherlock tilted his head to the side, his eyebrows furrowed in frustration. "Damn, I _hate_ these agents," Sherlock muttered.

John stepped over a couple of bodies to get to his friend. "What about that last one?" he asked in undertone. "The … uh … flying one."

" _Flying_?" Sherlock scoffed, his eyes still lingering on Natasha. "Don't be absurd, John."

"Um, Sherlock …" John said, and Sherlock's gaze moved to the Vision.

" _Oh_ ," Sherlock said, rather faintly.

"Yep," John agreed.

"What _are_ you?" breathed Sherlock, his eyes wide.

"Synthetic humanoid," Natasha said simply, as if it was no big deal, brushing past the detective to have a better look at the bodies. John stifled a laugh at Sherlock's irritated expression.

"Director Fury," Steve said urgently. "Something's happened back at the HQ but Wanda told us not to come back. So we didn't. It sounded serious. Apparently, as she put it, everyone's 'down'."

Fury frowned. "We'll deal with that later. One problem at a time. For the moment, this is more urgent. The entire country of Singapore has been infected, and as much as we _care_ about our friends, this is slightly more important."

"Wait," John said, flushing slightly when the two men looked at him questioningly. "Um... ahem. Well, what if the two events aren't coincidental? They could be interconnected. If the people at your headquarters are 'down', that could mean 'unconscious', right? Maybe this … infection has hit New York."

"Wanda told me someone was after her, though," the super soldier pointed out.

"Well, the bloke who started all this … the man with the weird black energy smoke stuff … seemed to be unaffected by the stuff. He didn't pass out. Perhaps it's possible for someone to carry the disease, and infect others with it. That could have happened in NY as well."

Fury started at him, and John felt a self-conscious flush rising to his cheeks again. God, how he hated being the centre of attention. "I think you might be right, Dr Watson," said the Director. "You know, maybe you should be our new Avenger instead of Holmes. You've certainly helped us as much as he has."

"Wow, thank you, Director," mumbled John, and he meant it. It was probably the first time that someone had complimented his intelligence over Sherlock's.

"We've got to get this sorted out," Natasha declared. "What do you need us to do Fury?"

Fury opened his mouth to speak, before closing it abruptly, his single eye widening as he saw something over John's shoulder.  
"Oh my god," Steve gasped.  
"Second that," agreed Sam.

His throat tight and his heart hammering, John slowly turned around. The sight he saw was certainly one of the weirdest that he had seen in all his years working with Sherlock, and it was a sight that made his toes curl, his skin prickle and caused shivers to spiral down his spine.

"Holy sh*t," he breathed.

A woman (in fact, the very woman John had been inspecting earlier) was stood behind Sherlock and Natasha, her head bent at an odd angle, her arms sticking out crookedly in positions that shouldn't have been possible for a human body to master. Blood trickled across her skin, though John could see no visible injuries _,_ and beneath the red, her skin was as pale as bone. The woman's lips were bared in a disturbingly forced smile.

But the worst part was her eyes.

They were black, totally black, no pupil, no iris, nothing.

"This is a prank," Sam said, stepping backwards. "This has to be a prank."

The girl stepped forward, and Natasha and Sherlock quickly retreated to join the other five. She raised her hands and shadows began to flow slowly out of her fingertips, spiralling through the air like grotesque snakes.

"Is she possessed or something?" Natasha whispered, looking at Fury.

More of bodies began to rise from the ground with mechanical smoothness, limbs crooked and eyes dark. Like zombies, they began to move towards the Avengers, Fury, John and Sherlock.

"It's the infection," Sherlock said quietly, his hand moving to the gun that he had somehow managed to sneak onto the plane. "It's exactly twenty-four hours since they first were infected, and apparently this is the desired effect." He raised the gun, pointing directly at the first woman's head, and his finger on the trigger.

"Don't shoot," Fury ordered him. "They're still human."

"I'm afraid that they're not, Director."

Everyone turned to look at the Vision, who had been silent until now. John was surprised to hear that his accent was English. For some reason, he had expected it to be American, as he was _created_ by Americans.

"What do you mean?" Fury demanded.

"The disease has completely overridden their minds," Vision explained. "Unlike most so-called 'possessions', it is impossible for them to regain their formal mental state, according the analysis I just made of the energy they are emitting from their fingertips. If I am not mistaken, these victims of the ailment have as much potential to infect other humans with the symptoms as the original bearer of the illness did. This is because the black energy is the disease in the purest form."

Everyone stared at him.

"Why the hell didn't you say so before, god dammit?" Fury looked … furious. "Run! All of you, make for the plane that Captain Rogers and the others arrived on! _Run_!"

And they did.

* * *

 **Review or face the horror of whatever the heck this 'disease' is (THE MYSTERY! THE SUSPENSE! ALL WILL BE REVEALED ... SOON!)!**


	6. Chapter 6

**Guys! I'm back! I'm still alive! I haven't been eaten by bilgesnipe!**

 **Okay, yikes, I haven't updated this in ages, and I don't really have an excuse, other than the fact that I've been really busy. I also rewrote this chapter about ten times. So yeah.**

 **Anyways, new followers! Thanks, guys! :D**

 **Has everyone seen the Sherlock special trailer yet?! It looks so good!**

 **Sorry, I'm rambling. Hope this chapter is okay. Like I said, it took a while to get it right. If you notice any mistakes or anything that doesn't make sense feel free to tell me! :)**

Chapter 6

A car pulled up in front of the Avengers Facility. The whisper of the wheels on the tarmac were the only sound in the unearthly silence, followed by the sharp clack of high heels as Pepper Potts stepped out from the passenger side. The other door opened and Tony joined her.

"It looks deserted," Pepper observed, frowning. "Where is everyone?"

Tony tapped a code onto his phone. "I have no idea, but the CCTV feeds show that no one's left the building since Cap and the team left more than twelve hours ago."

"Are you sure Rhodey didn't just have his phone off?" she asked.

"I'm sure." He held the phone up so the whole building was visible through the screen, flickering blue and green. "That's kind of weird. No thermal radiation – apparently, no one's alive in there."

"They're all dead?" his girlfriend gasped, and her eyes widened dramatically. "Oh my god. Oh my god, what are we going to do?"

"It's fine," Tony said soothingly. "It's … probably fine. There could just be a malfunction in the phone's thermal camera, or something …" He trailed off as F.R.I.D.A.Y. informed him over the speaker that, no, the thermal camera was working just fine. "Oh. That's not good."

They had got the phone call yesterday evening.

"It's probably nothing," Rhodey had said. "But someone's broken in to the east wing of the Facility, CCTV's down, and the agents on duty in that area aren't responding over the comms. Wanda and I are going over there now. If I don't call back before … say, tomorrow at midday … well, you might wanna get over here and sort out whatever's killed us."

"Ever the optimist."

"Yeah, well, just in case, okay? Anyway, Rogers and everyone else are away in Singapore or somewhere, they just left an hour or so ago. So Scarlet Witch and I have gotta go kick some bad guy ass … _what_? Sh*t, what the hell? Tony –"

Then the line had gone silent for a moment, and there was the sound of gunfire in the background.

"Rhodey, what's going on?"

"Sh*t, this is bad, this is bad …"

"Rhodes!"

"Just, just don't come back okay? If I don't call back … just, don't come back. Seriously – _what,_ Wanda? Oh my god, oh _my god_ , oh –" The line cut off.

Rhodey didn't call back at midday, and when Tony had tried to contact him, his phone was dead. Obviously, he ignored Rhodey's instruction to not return, because if his friend had been hurt …or _worse_ … he was definitely not going to let whoever did it get away with that.

So here they were.

"The buildings in lockdown," Tony told Pepper, frowning at his phone screen. "Whatever's happened, it's triggered the HQ's emergency protocol. There's a force-field like the one at Baron Strucker's research base. I can hack the system, shut it down …" His fingers flew across the screen. "Wait a moment... there we go."

"Why did Steve and the others go to Singapore?" Pepper asked, as they walked cautiously forward.

"No idea. Fury doesn't tell me anything. I'm not technically an Avenger anymore, remember?" He raised a hand, tapped seemingly empty air. However, a force field flickered into existence, silver pixels shimmering with the impact, before disappearing again. Tony nodded. "I thought this would happen. They've got a hidden firewall in the network."

"Can you break it?"

"Yeah. Just give me a second …" He swiped at his phone once more, before looking up and raising an experimental hand. The billionaire punched the force field, ionised air-plasma particles scattering around him like shattered glass as the barrier dissipated.

Tony grinned. "That was cool." And then he groaned. "Damn, I've not brought the suit. We're completely unprotected and we have no idea what's going on the in Facility."

"Actually," Pepper said sheepishly. "I, um, brought back up." She produced two small handguns from her purse.

The engineer stared at her, and took one of the guns off her. "I'm not even gonna _ask_ where you got these."

"Happy gave them me. Apparently keeping pepper spray in my purse isn't a good enough defence after all we've been through. Come on, let's go inside."

He followed her across the drive. "Happy let you put _loaded guns_ in your _purse_? Isn't that dangerous? He didn't give you, like, a … a _thigh holster_ or whatever, like Natasha has?"

"Nope."

"I'm going to fire him."

They reached a metal door set in the west wing of the building, and it slid mechanically open when Tony typed an access code into the keypad. "We're in."

"Is this safe?" Pepper whispered as the two of them stepped tentatively inside. "There could be anything in here."

"I know."

Surprisingly, the corridor was empty – unnervingly empty. Tony wasn't sure what he was expecting, whether it was for the corridor to be bustling, full of agents and scientists going about their daily jobs, or whether he thought it would be full of corpses, but he wasn't anticipating emptiness.

The place was filled with the eerie, unsettling atmosphere of _kenopsia_ – the feeling of a place that is usually full of energy, but is now devoid of people. There was also something else there, too, another atmosphere – one that felt cold, like death.

"Can you feel it?" Pepper whispered, and he knew she felt it too. He nodded.

"Something's very wrong here."

Silently, the two of them traversed the lonely corridors, until they reached the centre of the building. The corridors were no longer empty.

Bodies were scattered and slumped on the floor, collapsed in doorways and leaning against the walls. They were everywhere, everyone – scientists, engineers, agents, soldiers – anyone who worked for Fury and Hill and the Avengers.

"My god," Pepper breathed, her hand jumping to cover her mouth.

Tony felt sick. He _knew_ these people – had talked to some of them, passed them on the Helicarrier, worked with them. And now they were all dead. No … wait.

"They're not dead. Look – they're breathing." He took her hand, and together they weaved their way around the bodies, and into the next corridor. It was just as bad there – it seems everyone in the building was unconscious. "What _happened_?"

Finally, they reached the east wing of the building, and a familiar glimpse of dark grey and silver caught Tony's eye. "Rhodey!"

War Machine was lying on the white marble floor like everyone else, suit still on, face plate opened. "Oh god, oh god," Tony hissed, crouching beside his friend. "What's going on?"

"Iron Man," said a mocking voice from across the room, and the two of them turned in surprise to see a woman stood there. "What a lovely surprise. You and your pathetic girlfriend will be perfect. You really deserve to be cured."

"Cured? What? Who are you?" Pepper asked, frowning. "Did you do this?"

"She looks evil," Tony commented, standing up and tilting his head to one side before nodding. "Yup. She looks evil."

"Evil?" The woman laughed, beginning to walk towards them. "That's a twisted way to look at things. I'm simply helping these people, Stark. When they awake tomorrow, they will be perfected."

Pepper glanced at him, and he nodded, giving her a look that said 'distract her'.

"Perfect how?" the CEO said, folding her arms.

"Friday, send in Mark 45," Tony whispered into his phone, hoping that he wouldn't be heard.

"Already on it, Sir. Mark 45 has been deployed. ETA: approximately fifty-eight seconds from now."

The woman smiled at Pepper. "Humanity is flawed. Their ideas, their emotions, their ambitions – it's dangerous, and all for a lost cause. It's sickening, the way people treasure their individuality, wanting to be better than everyone around them. Of course, they're not. They're not as good as him."

 _Thirty-five seconds._

"Who's 'him'?" the mechanic demanded, standing beside Pepper. His eyes narrowed. "You're sounding a little too much like my recently deceased, insane, robotic kind-of-son for me to agree with you on that sentence. Not that I would anyway. Because, um, you're evil," he ended lamely.

 _Twenty seconds._

In the corner of his eye, Tony could see Pepper's hand tighten around the gun, finger poised on the trigger. He tried to catch her eye, to shake his head slightly, but it was too late.

 _Ten seconds._

She raised her arm, and fired. The three of them watched as the bullet whooshed forwards, and hit the wall about a foot away from the woman's head. The woman smiled, began to speak –

And Mark 45 crashed through the glass wall to Tony's right.

Immediately, the suit opened, and Tony stepped inside, the metal snapping shut around him. He raised his hand, energy building up in the jet repulsor, ready to fire.

"Talk, fast, or the contents of your skull will be smeared all over that lovely cream wall, that I really don't want to ruin any further. Agent Hill wouldn't be very pleased with me."

She smirked. "Your armour is nothing compared to the Cure."

"Wanna bet?" he shot back, and fired, but not before dark energy curled from her hands, a tendril flowing into Pepper's chest. The laser hit her and she flew backwards, crashing to the wall and slumping to the ground, causing the rest of the energy to dissolve into the air. At the same time, Pepper dropped gracefully to the floor.

"Pepper!" Tony yelled, stepping out of the armour and sprinting towards her, dodging the unconscious bodies littered across the floor. " _Pepper_!"


	7. Interlude

Hello! Sorry to disappoint, but this isn't a story update – I'm just here to inform you guys that although I haven't updated for over a year, this story hasn't been abandoned!

I do plan on eventually getting around to updating it – I fell out of the fandom(s) for a little while and have been very busy (with dreadful writers block on top of that).

Thank you for all the lovely new reviews, you're all wonderful

Feel free to come and nag me to update on my tumblr ( avengerwarlockdetective) if the next chapter is still a no-show in the next few months.

Again, I'm very sorry, and I will hopefully update in the near future.


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